fix: remove dead chat_stream endpoint and body-based stream detection

The "stream" in endpoint check was dead code — both V1 and V2 SDK always
route through endpoint "chat" (v1/chat and v2/chat paths). Streaming is
reliably signalled via body["stream"], which the SDK always sets.

- Drop "stream" in endpoint guard on is_stream and isStream detection
- Remove "chat_stream" from action_map, transform, and response branches
- Update unit tests to use "chat" endpoint (the only real one)

Author: fede-kamel

src/cohere/oci_client.py

@@ -480,7 +480,7 @@ def _event_hook(request: httpx.Request) -> None:
         request.stream = ByteStream(oci_body_bytes)
         request._content = oci_body_bytes
         request.extensions["endpoint"] = endpoint
-        request.extensions["is_stream"] = "stream" in endpoint or body.get("stream", False)
+        request.extensions["is_stream"] = body.get("stream", False)
         request.extensions["is_v2"] = is_v2_client
 
     return _event_hook
@@ -554,7 +554,6 @@ def get_oci_url(
     action_map = {
         "embed": "embedText",
         "chat": "chat",
-        "chat_stream": "chat",
     }
 
     action = action_map.get(endpoint)
@@ -658,7 +657,7 @@ def transform_request_to_oci(
 
         return oci_body
 
-    elif endpoint in ["chat", "chat_stream"]:
+    elif endpoint == "chat":
         # Validate that the request body matches the client type
         has_messages = "messages" in cohere_body
         has_message = "message" in cohere_body
@@ -800,7 +799,7 @@ def transform_request_to_oci(
                 chat_request["priority"] = cohere_body["priority"]
 
         # Handle streaming for both versions
-        if "stream" in endpoint or cohere_body.get("stream"):
+        if cohere_body.get("stream"):
             chat_request["isStream"] = True
 
         # Top level OCI request structure
@@ -861,7 +860,7 @@ def transform_oci_response_to_cohere(
             "meta": meta,
         }
 
-    elif endpoint == "chat" or endpoint == "chat_stream":
+    elif endpoint == "chat":
         chat_response = oci_response.get("chatResponse", {})
 
         if is_v2:
@@ -1096,7 +1095,7 @@ def transform_stream_event(
     Returns:
         V2: List of transformed events. V1: Single transformed event dict.
     """
-    if endpoint in ["chat_stream", "chat"]:
+    if endpoint == "chat":
         if is_v2:
             content_type = "text"
             content_value = ""

tests/test_oci_client.py

@@ -715,7 +715,7 @@ def test_v1_stream_wrapper_preserves_finish_reason(self):
 
         events = [
             json.loads(raw.decode("utf-8"))
-            for raw in transform_oci_stream_wrapper(iter(chunks), "chat_stream", is_v2=False)
+            for raw in transform_oci_stream_wrapper(iter(chunks), "chat", is_v2=False)
         ]
 
         self.assertEqual(events[2]["event_type"], "stream-end")
@@ -759,8 +759,6 @@ def test_get_oci_url_known_endpoints(self):
         url = get_oci_url("us-chicago-1", "chat")
         self.assertIn("/actions/chat", url)
 
-        url = get_oci_url("us-chicago-1", "chat_stream")
-        self.assertIn("/actions/chat", url)
 
     def test_get_oci_url_unknown_endpoint_raises(self):
         """Test that unknown endpoints raise ValueError instead of producing bad URLs."""